Neuroculture on the Implications of Brain Science
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Neuroculture On the implications of brain science Edmund T. Rolls Oxford Centre for Computational Neuroscience Oxford England 1 00-Rolls-FM.indd iii 8/13/2011 12:48:30 PM 1 Great Clarendon Street, Oxford ox2 6dp Oxford University Press is a department of the University of Oxford. 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Enquiries concerning reproduction outside the scope of the above should be sent to the Rights Department, Oxford University Press, at the address above You must not circulate this book in any other binding or cover and you must impose the same condition on any acquirer British Library Cataloguing in Publication Data Data available Library of Congress Cataloging in Publication Data Data available Prelims typeset in by Glyph International, Bangalore, India Printed in Great Britain on acid-free paper by CPI Antony Rowe, Chippenham, Wiltshire ISBN 978–0–19–969547–8 10 9 8 7 6 5 4 3 2 1 Whilst every effort has been made to ensure that the contents of this book are as complete, accurate and up-to-date as possible at the date of writing, Oxford University Press is not able to give any guarantee or assurance that such is the case. Readers are urged to take appropriately qualifi ed medical advice in all cases. The information in this book is intended to be useful to the general reader, but should not be used as a means of self-diagnosis or for the prescription of medication. 00-Rolls-FM.indd iv 8/13/2011 12:48:30 PM Preface Understanding how our brains work, and how evolution has shaped them, has interesting implications for understanding many aspects of human behaviour. To help understand ourselves this book describes the implications of our modern understanding of brain function for many different areas. They include emotion; social behaviour; rationality vs emotion; the philosophy of the relation between the mind and the brain, and of consciousness; aesthetics; ethics, economics; psychiatry; religion; and politics. It is argued that a new type of understanding of these issues can emerge from the developments in understanding the brain and behaviour that are emerging from modern neuroscience, and how our brains have been shaped by evolution. This new understanding may have important implications for understanding the forces at work in areas such as emotional and social behaviour, economics, aesthetics, ethics, and politics. The author brings a unique perspective to these issues, which can be grouped together as neuroculture, because of his approach to understanding the brain and biological mechanisms of emotion (Emotion Explained, 2005, Oxford University Press) which he now argues has implications for our understanding of aesthetics, sociality, ethics, and economics; and because of his approach to how the brain works at the mechanistic, i.e. neurobiological and computational, level (Memory, Attention, and Decision•Making: A Unifying Computational Neuroscience Approach, 2008, Oxford University Press; The Noisy Brain: Stochastic Dynamics as a Principle of Brain Function, 2010 with G.Deco, Oxford University Press) which is important for understanding human choices, decision•making, economics, psychiatry, normal aging, and relations between mental and physical events. By combining rigorous neuroscientific approaches both to the evolutionary adaptive value of emotion and how this has shaped our brains, and to brain computation (i.e. how the brain works), the author brings a rational, fundamen• tal, and new approach to these issues in the new area of Neuroculture. Each area covered is prefaced by the term ‘neuro’, to emphasize that it is the impli• cations of our understanding of brain function that is being investigated in each chapter. The areas covered include Neuroaffect (Chapter 3); Neurosociality (Chapter 4); Neuroreason (Chapter 5); Neurophilosophy (Chapter 6); Neu• roaesthetics (Chapter 7); Neuroeconomics (Chapter 8); Neuroethics (Chapter vi j Preface 9); Neuropsychiatry (Chapter 10); Neuroreligion (Chapter 11); and Neuropoli• tics (Chapter 12). Chapter 2, Neuroscience, introduces how we understand how the brain works, how it computes, at the level of the operations of brain cells, and of networks of brain cells, focusing on areas that help to provide a foun• dation for understanding these fascinating questions of emotion, rationality, decision•making, and memories that shape our lives, feelings, and behaviour. Some of these areas are developing rapidly, for example neuroethics, but the author seeks to bring an original approach to these areas, by building on his expertise in the brain mechanisms and evolutionary bases of emotion, and in computational neuroscience, to develop an understanding of why our brains operate as they do, and what the implications are. The approach taken in this book is based on an understanding of the ac• tual mechanisms by which the brain functions, as well as the evolutionary pressures that have led to the design of our brains. The approach thus goes be• yond evolutionary psychology (or sociobiology), which considers behavioural adaptations shaped by evolutionary pressure, but has not taken the brain mech• anisms involved into account in a direct way. Understanding the brain mecha• nisms involved helps us to understand reward processes and thereby to address aesthetics, emotion, decision•making, ethics, free will, and economics. Under• standing the brain mechanisms involved in detecting causality helps one to address religion. Understanding the brain processing at the mechanistic level also provides a way to address how alterations in brain systems may lead to psychiatric and behavioural dysfunctions, which may then, in the light of our understanding of how they are implemented in the brain, become more easily treatable. The approach based on what the brain computes, and how it com• putes, is thus important in the approach taken in this book to a wide range of issues. The approach is fresh, for it seeks to understand many of the ways in which we behave by understanding some of the difficult computational prob• lems faced by the brain, and the types of solution that the brain has found to these computational problems. The overall aims of the book are developed further, and the plan of the book is described, in Chapter 1, Section 1.1. The material in this text is the copyright of Edmund T. Rolls. Part of the material described in the book reflects work performed in collaboration with many colleagues, whose tremendous contributions are warmly appreciated. The contributions of many will be evident from the references cited in the text. I dedicate this book to them; to many scientific colleagues including Colin Blakemore, Marian Dawkins, and Larry Weiskrantz whose integrity and support have been outstanding; and to colleagues in other areas who have inspired me, including the sculptor, artist, and musician Penny Wheatley, and the philosopher David Rosenthal. Much of the work described would not have been possible without financial support from a number of sources, particularly Preface j vii the Medical Research Council of the UK, the Human Frontier Science Program, the Wellcome Trust, and the James S. McDonnell Foundation. The book was typeset by the author using LaTeX and WinEdt. The cover shows part of the picture The Birth of Venus painted by San• dro Botticelli in c. 1486. The metaphor is that Botticelli was thinking about the origins of love, and beauty. I, in this book, am considering the scientific foundations of love, beauty, aesthetics, ethics, and many related aspects of our being in terms of how different evolutionary forces have shaped our brains, our emotions, and our rationality. Updates to some of the publications cited in this book are available at http://www.oxcns.org. I dedicate this work to the overlapping group: my family, friends, and colleagues – in salutem praesentium, in memoriam absentium. Contents 1 Introduction 1 1.1 The framework 1 1.2 Genetic influences on behaviour by adaptations of the brain 4 2 Neuroscience 9 2.1 Introduction 9 2.2 Neurons 10 2.3 Information encoded in the brain by neuronal firing rates 10 2.3.1 Reading the code used by single neurons 10 2.3.2 Understanding the code provided by populations of neurons 17 2.4 What neurons do: neuronal computation 24 2.5 Learning implemented in different neuronal network architectures 27 2.5.1 Learning implemented by associative synaptic modification 27 2.5.2 Pattern association memory 29 2.5.3 Autoassociation or attractor memory 30 2.5.4 Competitive networks 35 2.5.5 Stochastic dynamics: integrate•and•fire